Substring value retrieved from database in .NET / C#

Question

I'm using the following to read out values from my database:

    while (reader.Read())
    {
        newsLabel.Text += "<div style='float:left;'>" + reader["body"] + "</div>";
    }

I was wondering. How do I reduce the value of "body" to just 0,20 characters?

Is there a Substring function I can use?

Many thanks

Answer 1

Assuming that the body column contains a string you can truncate it like this:

var body = (String) reader["body"];
var truncatedBody = body.Substring(0, Math.Min(body.Length, 20));

If the column can be null you will have to check for that before calling Substring.

Substring will throw an exception if the requested length of the substring is longer than the length of the actual string. That is why you have to use the minimum of the string length and the desired substring length.

If you do this a lot you can create an extension method:

public static class StringExtensions {

  public static String Truncate(this String str, Int32 length) {
    if (length < 0)
      throw new ArgumentOutOfRangeException("length");
    if (str == null)
      return String.Empty;
    return str.Substring(0, Math.Min(str.Length, length));
  }

}

You can use it like this:

((String) reader["body"]).Truncate(20)

Answer 2

You can do that as shown below. Make sure to check for DbNull.

while (reader.Read()) 
        {
            string body = reader["body"] is DBNull ? "" : Convert.ToString(reader["body"]);

            if(body.Length > 20)
              body = body .Substring(0, 20);

            newsLabel.Text += "<div style='float:left;'>" + body  + "</div>";   
        }